The legislation, at least the one coming from Brussels, is nearly always reasonable in scope, extent, impacts, penalties, and tends to strike a fair balance between specificity and vagueness as to allow the courts for some wiggle room for interpretation
As an example, with interoperability, the final legislation might stipulate something similar to this:
* once a software service reaches sufficient market size
* the core functionality of the service must be exposed for interoperability
* any breaking changes to core functionality must allow for sufficient period of backwards-compatibility and deprecation warnings. Exceptions for security breaches or other emergencies
So, for Youtube, this would mean logging in, viewing videos and history. It doesn't mean that every single feature of every single web site must be publicly exposed and be backwards-compatible for eternity